This invention relates to intraocular lenses (IOL's) and in particular to IOL's that reduce or even eliminate irritation of the ciliary band in the eye and reduce the incidence of papillary block, and, if a natural crystalline lens is present, to reduce the risk of cataract formation.
IOL's are commonly used to modify vision. For example, IOL's are used to replace the natural lens of the eye when warranted by medical conditions. A common practice is to implant an IOL in a region of the eye known as the capsular bag or posterior capsule. However, in this practice, cells from the eye tend to grow on the capsular bag in front of and/or in back of the optical portion of the IOL. This tends to block the optical portion of the IOL and impair vision.
IOL's may be implanted in regions of the eye other than in the capsular bag. Referring now to Prior Art FIG. 1, an anterior IOL (AIOL) 10 is shown implanted in an eye 12. The eye 12 is comprised of a cornea 14 shown to the left and an iris 16 shown in the middle of the eye. It is to be understood that the cornea 14 is at the front of the eye 12. The iris 16 divides the eye 12 into an anterior chamber 18 at the front of the eye and a posterior chamber 20 in back of the iris. The iris 16 also defines the pupil 22, which is an opening in the middle of the iris. In front of the iris 16 is the scleral spur 24. The scleral spur 24 and the iris 18 delimit the ciliary band 26. Behind the iris 16 is the ciliary process 28, from which extends the ciliary muscle 30. The ciliary muscle supports the natural crystalline lens 32 of the eye 12. The iris 16 and the ciliary process 28 define the sulcus 34.
Prior Art FIG. 1 shows the AIOL 10 implanted in the anterior chamber 18 of the eye 12. The AIOL 10 is comprised of an optic 40 that is supported in front of the pupil 22 by loops or haptics 42. The optic 40, for the AIOL 10 and other IOL's described herein, may be considered as including an optical portion for focusing light at or near the retina (not shown) of the eye 12. The haptics 42 extend from the optic 40 and rest in the ciliary band 26. The haptics 42 are designed to minimize compression stress on the optic 40 and inhibit forward vaulting of the optic. If the optic 40 vaults and contacts the cornea 14, an undesirable condition known as endothelium tough may occur. However, this condition may occur from the haptics 42 merely residing in the ciliary band 26.
Referring now to Prior Art FIG. 2, the eye 12 now has a posterior IOL (PIOL) 50 implanted therein. The PIOL 50 is comprised of an optic 52 that is supported behind the pupil 22 by loops or haptics 54. The haptics 54 extend from the optic 52 and rest against the sulcus 34. In terms of inhibiting endothelium tough, the PIOL 50 is superior to the AIOL 10 as the opportunity for any part of the PIOL to contact the cornea 14 is greatly reduced. However, the PIOL 50 has increased opportunity for contacting the natural crystalline lens 32 due to their proximity. Having any object contact the lens 32 is undesirable as it may result in the incidence of papillary block and cataract formation.
It would be advantageous to provide an intraocular lens that reduces, or even minimizes, both the risks of endothelium tough and of papillary block.